Multiport cryopump

• US 4,446,702 A
• Filed: 02/14/1983
• Issued: 05/08/1984
• Est. Priority Date: 02/14/1983
• Status: Expired due to Term

• Current Assignee: Helix Technology Corporation (Azenta, Inc.)
• Original Assignee: Helix Technology Corporation (Azenta, Inc.)
• Inventors: Bartlett, Allen J., Peterson, John F.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US06/466,122
• Time in Patent Office: 449 Days
• Field of Search: 62/55.5, 62/100, 62/268, 417/901, 55/269
• US Class Current: 62/55.5
• CPC Class Codes: F04B 37/08 by condensing or freezing, e.g. cryogenic pumps
• CPC Class Codes: Y10S 417/901 Cryogenic pumps

Abstract

A cryopump installation in which a novel cryopump 20 maintains a work chamber 12 at continuous high vacuum while periodically evacuating a load lock 14 in order to allow transfer of material from the load lock 14 to the work chamber 12 without disruption of the work chamber environment. The cryopump has pumping ports 46 positioned on the radiation shield 50 in order to pump plenum 72 to a high vacuum. Load lock gases enter the cryopump through port 46 and are condensed and adsorbed by the radiation shield 50 and second stage cryopanel 54.

Claims

1. A cryopump system comprising:

a. a work chamber;

b. a load lock for receiving material to be introduced into the work chamber;

c. a cryopump housing in fluid communication with each of the work chamber and load lock;

d. a two stage refrigerator within the cryopump housing;

e. a second stage cryopumping surface in thermal contact with the second stage of the refrigerator; and

f. a radiation shield in thermal contact with the first stage of the refrigerator within the cryopump housing surrounding the second stage cryopumping surface, the shield having a frontal opening for providing gas communication from the working chamber to the second stage cryopumping surface and a rear opening for providing gas communication from the load lock to the second stage cryopumping surface.

2. A cryopump system as claimed in claim 1 wherein the radiation shield is in close proximity to the cryopump housing to provide a flow restriction therebetween.

3. A cryopump system as claimed in claim 1 wherein the rear opening is covered by a baffle to block transmission of radiation to the second stage refrigerator.

4. A cryopump system as claimed in claim 1 wherein an extension from the radiation shield surrounds but does not contact a conduit from the load lock.

5. A cryopump system as claimed in claim 4 wherein the extension includes baffles therein for blocking radiation from the conduit and the load lock from impinging on the second stage cryopumping surface.

6. A cryopump system comprising:

a. a housing enclosing a first and second stage cryogenic refrigerator;

b. a first work chamber in fluid communication with both stages of said refrigerator through a first port in the housing;

c. a second chamber in fluid communication with both stages of said refrigerator through a second port in the housing;

d. a frontal cryopanel extending across said first port and in thermal communication with a first stage of said refrigerator; and

e. baffle means between said second port and the second stage of said refrigerator and in thermal communication with said first stage of said refrigerator for preventing direct transfer of heat radiation between said second port and said second stage refrigerator.

7. A cryopump comprising:

a. a cryopump housing, said housing having a first port for attachment to a first work chamber;

b. a refrigerator within said housing having first and second stages;

c. a second stage cryopanel mounted to a low temperature heat sink on the second stage;

d. a radiation shield partially enclosing said second stage cryopanel, coaxial with the refrigerator and in thermal contact with an intermediate temperature heat sink on the first stage;

e. a frontal cryopanel extending across a first opening in the radiation shield adjacent said first port to said work chamber, the frontal cryopanel being in thermal contact with the first stage of the refrigerator;

f. a second port in the cryopump housing, said second port removed from said work chamber and in fluid communication with a second chamber;

g. a second opening in the radiation shield in fluid communication with said second port in the refrigerator housing.

8. A cryopump as claimed in claim 7 further comprising baffle means adjacent to said second opening for deflection of gases from direct communication with said second stage cryopanel.

9. A cryopump as recited in claim 7 wherein said second opening in the radiation shield maintains low pressure in the area of the cryopump removed from said first port in order to reduce heat load on the refrigerator.

10. A cryopump as recited in claim 7 further comprising seal means positioned between the cryopump housing the radiation shield in order to further restrict fluid communication between said first and second ports.

11. A method of continuously processing material in a high vacuum chamber comprising the steps of:

a. reducing work chamber pressure to a system operating pressure by means of a work chamber cryopump;

b. introducing material into a load lock;

c. reducing the load lock pressure to an intermediate pressure by means of a roughing pump;

d. isolating the load lock from said roughing pump;

e. reducing said load lock intermediate pressure to about work chamber pressure by means of the work chamber cryopump;

f. connecting said work chamber to said load lock; and

g. transferring said material from the load lock to the work chamber.